Differential Gene Expression by RamA in Ciprofloxacin-Resistant Salmonella Typhimurium

Overexpression of ramA has been implicated in resistance to multiple drugs in several enterobacterial pathogens. In the present study, Salmonella Typhimurium strain LTL with constitutive expression of ramA was compared to its ramA-deletion mutant by employing both DNA microarrays and phenotype microarrays (PM). The mutant strain with the disruption of ramA showed differential expression of at least 33 genes involved in 11 functional groups. The study confirmed at the transcriptional level that the constitutive expression of ramA was directly associated with increased expression of multidrug efflux pump AcrAB-TolC and decreased expression of porin protein OmpF, thereby conferring multiple drug resistance phenotype. Compared to the parent strain constitutively expressing ramA, the ramA mutant had increased susceptibility to over 70 antimicrobials and toxic compounds. The PM analysis also uncovered that the ramA mutant was better in utilization of 10 carbon sources and 5 phosphorus sources. This study suggested that the constitutive expression of ramA locus regulate not only multidrug efflux pump and accessory genes but also genes involved in carbon metabolic pathways

Developing of Bluetooth Mesh Flooding Between Source-destination Linking of Nodes in Wireless Sensor Networks

Bluetooth uses 2.4 GHz in ISM (industrial, scientific, and medical) band, which it shares with other wireless operating system technologies like ZigBee and WLAN. The Bluetooth core design comprises a low-energy version of a low-rate wireless personal area network and supports point-to-point or point-to-multipoint connections. The aim of the study is to develop a Bluetooth mesh flooding and to estimate packet delivery ratio in wireless sensor networks to model asynchronous transmissions including a visual representation of a mesh network, node-related statistics, and a packet delivery ratio (PDR). This work provides a platform for Bluetooth networking by analyzing the flooding of the network layers and configuring the architecture of a multi-node Bluetooth mesh. Five simulation scenarios have been presented to evaluate the network flooding performance. These scenarios have been performed over an area of 200×200 meters including 81 randomly distributed nodes including different Relay/End node configurations and source-destination linking between nodes. The results indicate that the proposed approach can create a pathway between the source node and destination node within a mesh network of randomly distributed End and Relay nodes using MATLAB environment. The results include probability calculation of getting a linking between two nodes based on Monte Carlo method, which was 88.7428 %, while the Average-hop-count linking between these nodes was 8. Based on the conducted survey, this is the first study to examine and demonstrate Bluetooth mesh flooding and estimate packet delivery ratio in wireless sensor network